Gas flow distribution receptacles, plasma generator systems, and methods for performing plasma stripping processes

ABSTRACT

Systems, system components, and methods for plasma stripping are provided. In an embodiment, a gas flow distribution receptacle may have a rounded section that includes an inner surface defining a reception cavity, an outer surface forming an enclosed end, and a centerpoint on the outer surface having a longitudinal axis extending therethrough and through the reception cavity. First and second rings of openings provide flow communication with the plasma chamber. The second ring of openings are disposed between the first ring and the centerpoint, and each opening of the second ring of openings extends between the inner and outer surfaces at a second angle relative to the longitudinal axis that is less than the first angle and has a diameter that is substantially identical to a diameter of an adjacent opening and smaller than the diameters of an opening of the first ring of openings.

TECHNICAL FIELD

The present invention generally relates to systems, system components,and methods for plasma stripping and more particularly relates to gasflow distribution receptacles, plasma generators, and methods forperforming plasma stripping processes using such gas flow distributionreceptacles and plasma generators.

BACKGROUND

Plasma stripping, also known as plasma ashing, is a process of removingorganic matter and/or residue, such as photoresist, from a workpieceduring semiconductor processing. Typically, plasma stripping isperformed using a plasma generator. Conventional plasma generatorsinclude a tube, a coil, and a processing gas source. The tube may bemade of a dielectric material, such as quartz, and may be at leastpartially surrounded by the coil. An inner surface of the tube defines aplasma chamber that is in flow communication with the processing gassource to receive a processing gas therefrom. To diffuse the processinggas before injection into the plasma chamber, a gas flow distributionreceptacle, also made of a dielectric material, may be disposed over aninlet to the plasma chamber. The gas flow distribution receptacletypically includes a ring of evenly spaced openings to provide a flowpath between the processing gas source and the plasma chamber.

During operation, the coil is energized and creates an electric fieldacross the plasma chamber. As the processing gas flows through theelectric field within the plasma chamber, a portion of the processinggas becomes ionized and forms plasma. The plasma dissociates anotherportion of the processing gas and transforms it into reactive radicals.The reactive radicals flow to and deposit onto the workpiece, which isdisposed adjacent to a dispersion plate or showerhead of the plasmachamber, and react with the organic matter and/or residue thereon toform an easily removable ash or other material.

Although the aforementioned system yields high quality results, thesystem may be improved. For example, in instances in which theprocessing gas includes fluorine-comprising gases, such astetrafluoromethane (CF₄), reactive fluorine radicals may be producedwhen the fluorine-comprising gas passes through the electric field. Insome cases, the reactive fluorine radicals may chemically react with thequartz material of the gas flow distribution receptacle and/or the tubeto cause erosion or etching thereof. In other cases, the chemicalreaction may produce a silicon oxyfluoride (SiOF) film over the gas flowdistribution receptacle and/or the tube. To avoid these unwantedeffects, the gas flow distribution receptacle and/or tube are typicallyreplaced once erosion is detected. However, some fluorine-comprisinggases may erode or etch the components relatively quickly, and frequentreplacement of these components may undesirably increase maintenancecosts of the system.

Accordingly, it is desirable to have an improved plasma generator systemthat may be used in conjunction with fluorine-comprising processinggases such that the gases cause minimal etching of the systemcomponents. Additionally, it is desirable for the plasma generatorsystem to include components, such as gas flow distribution receptacles,with improved useful lives compared to components of conventional plasmagenerator systems to thereby decrease maintenance costs of such systems.Furthermore, other desirable features and characteristics of the presentinvention will become apparent from the subsequent detailed descriptionof the invention and the appended claims, taken in conjunction with theaccompanying drawings and this background of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and wherein:

FIG. 1 is a simplified, cross-sectional view of a plasma generatorsystem, according to an exemplary embodiment of the present invention;

FIG. 2 is a perspective view of a gas flow distribution receptacle thatmay be used in the plasma generator system depicted in FIG. 1, accordingto an exemplary embodiment of the present invention;

FIG. 3 is a close up view of a portion of the gas flow distributionreceptacle as indicated by dotted line 3-3 in FIG. 2, according to anexemplary embodiment of the present invention;

FIG. 4 is an end view of a gas flow distribution receptacle that may beused in the plasma generator system depicted in FIG. 1, according toanother exemplary embodiment of the present invention;

FIG. 5 is an end view of a gas flow distribution receptacle that may beused in the plasma generator system depicted in FIG. 1, according toanother exemplary embodiment of the present invention;

FIG. 6 is an end view of a gas flow distribution receptacle that may beused in the plasma generator system depicted in FIG. 1, according toanother exemplary embodiment of the present invention;

FIG. 7 is an end view of a gas flow distribution receptacle that may beused in the plasma generator system depicted in FIG. 1, according toanother exemplary embodiment of the present invention;

FIG. 8 is a diagram depicting flow of processing gas through a gas flowdistribution receptacle, according to an exemplary embodiment of thepresent invention; and

FIG. 9 is a flow diagram of a method for performing a plasma strippingprocess, according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION

The following detailed description of the invention is merely exemplaryin nature and is not intended to limit the invention or the applicationand uses of the invention. Furthermore, there is no intention to bebound by any theory presented in the preceding background of theinvention or the following detailed description of the invention.

FIG. 1 is a simplified, cross-sectional view of a plasma generatorsystem 100, according to an exemplary embodiment of the presentinvention. The plasma generator system 100 is configured to selectivelyremove organic material from a workpiece 102 via plasma stripping.Plasma stripping, also known as “plasma ashing,” may be employed toremove organic material, such as, for example, photoresist, organicresidues, and/or polymer residues, from the workpiece 102 to clean theworkpiece 102. In addition, plasma stripping also may be used to removebiological contamination from the workpiece 102, to enhance adhesion oflayers to the workpiece 102 prior to deposition of such layers, toreduce metal oxides on the workpiece 102, or to otherwise etch a rangeof materials from the workpiece 102.

The workpiece 102 may be a semiconductor substrate and may be made ofrelatively pure silicon, germanium, gallium arsenide, or othersemiconductor material typically used in the semiconductor industry, orof silicon admixed with one or more additional elements such asgermanium, carbon, and the like, in an embodiment. In anotherembodiment, the workpiece 102 may be a semiconductor substrate havinglayers that have been deposited thereover during a conventionalsemiconductor fabrication process. In still another embodiment, theworkpiece 102 may be a component, such as a sheet of glass, ceramic, ormetal, that may be subjected to plasma stripping to remove unwantedorganic materials thereon.

The plasma generator system 100 may be a remote, stand alone apparatusor an in-situ module that is incorporated into a processing system. Theplasma generator system 100 shown in FIG. 1 is an example of a remoteapparatus. In accordance with an exemplary embodiment of the presentinvention, the plasma generator system 100 includes a container 106, acoil 108, an energy source 110, a showerhead 112, and a gas flowdistribution receptacle 114. Although an in-situ module may not beconfigured identically to the embodiment shown in FIG. 1, it may includesimilar components.

The container 106 is configured to receive a processing gas that can beionized by an electric field and transformed into plasma suitable fordissociating the processing gas into reactive radicals and for removingorganic material from the workpiece 102. In an exemplary embodiment, thecontainer 106 is made of a material that is capable of enhancing theelectric field. For example, the container 106 may be made of adielectric material including, but not limited to quartz,aluminum/sapphire, and ceramic. To contain the plasma therein, thecontainer 106 has a sidewall 116 that defines a plasma chamber 118. Thesidewall 116 has any thickness that is suitable for containing plasmawithin the container 106 and that does not interfere with the electricfield produced by the coil 108. In an exemplary embodiment, the sidewall116 has a thickness in a range of from about 4 mm to about 6 mm. Inanother exemplary embodiment, the sidewall 116 has a substantiallyuniform thickness (e.g., ±0.5 mm) along its entire axial length. Instill another embodiment, the sidewall 116 has a varying thickness alongits axial length.

The sidewall 116, and hence, the plasma chamber 118, have a shapesuitable for allowing the plasma to be directed toward the workpiece102. In one exemplary embodiment, the sidewall 116 has a shape thatvaries along its axial length, as depicted in FIG. 1. For example, thesidewall 116 may include a neck section 120 extending from an inlet end122 of a concave section 124 and a tube section 126 extending from anoutlet end 128 of the concave section 124. The neck section 120 may becylindrical and may have an inlet 130 and a lip 132 that protrudesradially outwardly from an end 134 of the neck section 120 proximate theinlet 130. In one exemplary embodiment, the neck section 120 has asubstantially uniform diameter (shown as dotted line 113) (e.g., ±0.5mm) along its axial length. In another exemplary embodiment, the necksection 120 has a varying diameter. In yet another exemplary embodiment,the diameter 113 is in a range of from about 30 mm to about 60 mm.

The concave section 124 may be dome-shaped, cone-shaped, or may have anyother shape that is generally concave and that has an outlet enddiameter (shown as dotted line 115) that is greater than an inlet enddiameter (shown as dotted line 117). In one exemplary embodiment, theoutlet end diameter 115 is also greater than the diameter 113 of theneck section 120. In another exemplary embodiment, the outlet enddiameter 115 is in a range of from about 150 mm to about 350 mm, whilethe diameter 113 of the neck section 120 is in the range of from about30 mm to about 60 mm. In other embodiments, the diameters 115, 113 maybe larger or smaller than the aforementioned ranges. In accordance withanother exemplary embodiment of the present invention, the tube section126 has a substantially uniform diameter (shown as dotted line 119) thatis substantially equal (e.g., ±0.5 mm) to the outlet end diameter 115 ofthe concave section 124. In another exemplary embodiment, the diameter119 of the tube section 126 is greater than the outlet end diameter 115of the concave section 124. In yet another exemplary embodiment, thediameter 119 of the tube section 126 is in a range of from about 150 mmto about 350 mm, and the outlet end diameter 115 of the concave section124 may be in a range of from about 75 mm to about 300 mm. In otherembodiments, the diameters 119, 115 may be larger or smaller than theaforementioned ranges.

The tube section 126 includes an outlet 138 from the plasma chamber 118that may be at least as large as a diameter of the workpiece 102. In anexemplary embodiment, the outlet 138 has a diameter (depicted as dottedline 121) that is in the range of from about 150 mm to about 350 mm. Inanother exemplary embodiment, the outlet 138 has a diameter 121 that issmaller than or larger than the aforementioned ranges. For example, inembodiments in which only a desired portion of the workpiece 102 is tobe subjected to plasma stripping, the diameter 121 of the outlet 138corresponds to the size of the desired portion.

To allow the processing gas to transform into plasma, the coil 108surrounds at least a portion of the container 106. In one exemplaryembodiment, the coil 108 is disposed around at least a portion of theconcave section 124. For example, in embodiments in which the concavesection 124 is a dome or cone, the coil 108 may be positioned betweenthe inlet end and the outlet end 128 thereof, as illustrated in FIG. 1.In another exemplary embodiment, the coil 108 additionally, oralternatively, surrounds the tube section 126. In any case, the coil 108is made of a conductive material, such as, for example, copper, and iselectrically coupled to the energy source 110. The energy source 110 maybe a radio frequency (RF) voltage source or other source of energycapable of energizing the coil 108 to form an electric field. Thus, whenthe energy source 110 energizes the coil 108, the electric field isformed in a selected portion of the plasma chamber 118 to thereby ionizethe processing gas that may flow therethrough to form ionized gas. Asused herein, the term “ionized gas” may include, but is not limited to,ions, electrons, neutrons, reactive radicals, dissociated radicals, andany other species that may be produced when the processing gas ionizes.

A showerhead 112 may be positioned at the plasma chamber outlet 138 tocontrol dispersion of the ionized gas, which may include reactiveradicals, across the work piece 102. In one exemplary embodiment, theshowerhead 112 includes a plate 140. The plate 140 may be made from anysuitable material that is relatively inert with respect to the plasma,such as aluminum or ceramic. Generally, the plate 140 is sized to allowgas dispersion over an entirety of the workpiece 102 and thus, has acorrespondingly suitable diameter. To allow gas passage therethrough,the plate 140 is relatively porous. In particular, the plate 140includes through-holes 144 that are suitably sized and spaced todisperse the ionized gas over the work piece 102 in a substantiallyuniform manner. In one exemplary embodiment, the through-holes 144 havea diameter in a range of from about 2 mm to about 10 mm. In anotherexemplary embodiment, the through-holes 144 are present at a surfacedensity in a range of from about 0.005 holes/mm² to about 0.2 holes/mm.In other embodiments, the through-holes 144 have larger or smallerdimensions than the ranges previously provided. In another exemplaryembodiment, the through-holes 144 are substantially uniformly sized(e.g., ±0.5 mm). Additionally, the through-holes 144 are disposed in asubstantially uniform pattern on the showerhead 112, in one exemplaryembodiment but, in another exemplary embodiment, the through-holes 144are disposed in a non-uniform pattern.

In an exemplary embodiment of the present invention, the showerhead 112is directly coupled to the container 106, as shown in FIG. 1. Forexample, the showerhead 112 may include sidewalls 142 that extendingaxially from the plate 140 and that are coupled to the container 106 viabolts, clamps, adhesives or other fastening mechanisms. In anotherexemplary embodiment, the showerhead 112 is not coupled to the container106 and the plate 140 is positioned at a desired location between theplasma chamber outlet 138 and the workpiece 102.

The processing gas may be diffused before injection into the plasmachamber 118 to uniformly distribute the gas thereto. In this regard, inone exemplary embodiment, the gas flow distribution receptacle 114 isdisposed in a plasma chamber inlet 136, which may or may not be locatedat the neck section inlet 130. For example, as shown in FIG. 1, the gasflow distribution receptacle 114 is disposed in a portion of the necksection 120 of the container 106. With additional reference to FIG. 2,to further enhance even distribution of the processing gas, the gas flowdistribution receptacle 114 has a cup member 150 with first and secondrings 152, 154 (rings depicted in phantom) of openings 182, 184 formedtherethrough.

The cup member 150 is made of a material that is non-conductive and iscapable of withstanding corrosion when exposed to the processing gas.Suitable materials include, for example, dielectric materials such asquartz. Additionally, in one exemplary embodiment, the cup member 150has a wall thickness that is substantially identical (e.g., ±0.5 mm) tothe thickness of the neck section 120 of the container 106. In otherembodiments, the cup member 150 may be thicker or thinner.

In any case, the cup member 150 may include a cylindrical section 156and a rounded section 160. The cylindrical section 156 may define aportion of a reception cavity 164 having an open end 158. Additionally,the cylindrical section 156 may have an outer diameter that is less thanthe inner diameter of the plasma chamber inlet 136. In an exemplaryembodiment, a flange 166 extends radially outwardly from the cylindricalsection 156. The flange 166 may be used to retain the gas flowdistribution receptacle 114 in position on the container 106 and may beclamped between a cover plate 168 and the container 106. In this regard,the outer diameter of the flange 166 is at least as large as a diameterof the neck section inlet 130. In an exemplary embodiment, the outerdiameter of the flange 166 is substantially equal (e.g., ±0.5 mm) to theouter diameter of the container lip 132. In other examples, the outerdiameter of the flange 166 may be larger or smaller. In anotherexemplary embodiment, the cover plate 168 has a diameter that issubstantially equal to (e.g., ±0.5 mm) or larger than an outer diameterof the flange 166. For example, the flange 166 may have an outerdiameter that is in the range of from about 40 mm to about 70 mm, andthe cover plate 168 may have a diameter that is larger. In otherembodiments, the diameters may be smaller or larger. A clamping fixture167 may surround at least the flange 166, the cover plate 168, and thecontainer lip 132 to ensure that the gas flow distribution receptacle114 remains disposed at a desired location on the container 106. Toallow access into the reception cavity 164, the cover plate 168 mayinclude one or more openings 170. The openings 170 may be configured toreceive one or more corresponding gas connection lines 172 to provideflow communication with a processing gas source 177.

The rounded section 160 is generally hemispherically-shaped and has aninner surface 165, an outer surface 169, and a centerpoint 173. Theinner surface 165 defines another portion of the reception cavity 164,and the outer surface 169 forms an enclosed end 162 of the gas flowdistribution receptacle 114. The centerpoint 173 is located on the outersurface 178 of the rounded section 160 and has a longitudinal axis 171that extends therethrough and through the reception cavity 164. Thefirst and second rings of openings 152, 154 are included on the roundedsection 160 and are adapted to provide flow communication between thereception cavity 164 and the plasma chamber 118.

To control the manner in which the processing gas is injected into theplasma chamber 118, the openings 182 of the first ring 152 are disposedwithin the rounded section 160 so that the processing gas flows alongpredetermined gas injection paths. The gas injection paths generallyallow the gas to flow axially from a first location in the receptioncavity 164 through openings 152 to a second location substantially(e.g., ±0.5 mm) at a center 174 of a plasma zone 176 (indicated bydotted circles). The plasma zone 176 is toroidally-shaped due to theplacement of the coils 108 around the container 106 and is identified byan area of the plasma chamber 118 having a highest density of plasmaduring plasma stripping. In an exemplary embodiment, the first locationis a point in the reception cavity 164 that optimizes a pressuredifference between the reception cavity 164 and the plasma chamber 118to thereby maximize a velocity of the processing gas, while minimizing adistance to the plasma zone center 174. For example, the first locationmay be a point in the reception cavity 164 that is substantiallyequidistant (e.g., ±0.5 mm) from each point on a circumference of aninner surface of the rounded section 160. It will be appreciated thatthe location of the first ring 152 of openings 182 on the cup member 150may depend on a particular location of the plasma zone center 174 withinchamber 118.

The number of openings 182 included in the ring 152, the size of theopenings 182, and the direction in which the openings 182 are formedrelative to the receptacle outer surface 169 may be further selected tofurther control the manner in which the gas is injected. For example, tosubstantially evenly distribute the processing gas within the plasmachamber 118, the first ring 152 of openings 182 may include twenty tothirty openings. In one particular example, twenty-four openings may beincluded, as shown in FIG. 2. In still other embodiments, more or feweropenings may be included. In one exemplary embodiment, the openings 182of the first ring 152 are disposed symmetrically about the longitudinalaxis 171 and are substantially evenly spaced around a circumference ofthe rounded section 160. In another exemplary embodiment, the openings182 of the first ring 152 are not evenly spaced around a circumferenceof the rounded section 160. For example, sets of two or more openingsmay be formed close together, and each set may be equally spaced fromthe longitudinal axis 171. In any case, the openings 182 are spaced suchthat the processing gas may be substantially evenly injected into theplasma chamber 118.

In one exemplary embodiment of the present invention, each opening 182of the first ring 152 has a diameter that is substantially identical(e.g., ±0.5 mm) to a diameter of an adjacent opening 182 in the firstring 152. In another exemplary embodiment, the openings 182 of the firstring 152 have diameters that vary within a range. For example, eachopening 182 may have a diameter that is within a range of from about 0.5mm to about 3.0 mm. In other examples, the openings 182 may be larger orsmaller than the aforementioned diameter range.

Turning to FIG. 3, a close-up cross-sectional view of a portion of thegas flow distribution receptacle 114 taken along line 3-3 of FIG. 2 isprovided. Each opening 182 of the first ring 152 of openings 182 extendsbetween the inner surface 165 and the outer surface 169 of thereceptacle 114 at a first angle (α) relative to the longitudinal axis171. In an exemplary embodiment, to more evenly disperse the processinggas into the plasma chamber 118, the first angle (α) is greater than 0°relative to the longitudinal axis 171 and, preferably, is in a range offrom about 30° to about 60°. For example, the first angle (α) may beabout 45°. In other embodiments, the first angle may be less than orgreater than the aforementioned range.

Returning to FIG. 2, the second ring 154 of openings 184 is configuredto form a flow curtain on an outer surface 178 of the rounded section160 of the gas flow distribution receptacle 114 during system operation.The flow curtain prevents a majority of the ionized gas in the plasmachamber 118, in particular, the reactive radicals, from depositing ontoand contacting the outer surface 178 of the gas flow distributionreceptacle 114. In this regard, the second ring 154 of openings 184 isdisposed between the first ring 152 of openings 182 and the centerpoint173 of the rounded section 160. FIG. 4 is an end view of a gas flowdistribution receptacle 400 that may be used in the plasma generatorsystem 100 depicted in FIG. 1, according to one exemplary embodiment.Gas flow distribution receptacle 400 is similar to gas flow distributionreceptacle 114 except that a second ring 402 of openings 184 is locatedequidistantly between a first ring 404 of openings 182 and a centerpoint406 of a rounded section 408 of the gas flow distribution receptacle400. FIG. 5 is an end view of a gas flow distribution receptacle 500that may be used in the plasma generator system 100 depicted in FIG. 1,according to another embodiment. In this embodiment, gas flowdistribution receptacle 500 is similar to gas flow distributionreceptacle 400 except that a second ring 502 of openings 184 is locatedcloser to a centerpoint 506 of a rounded section 508 than to the firstring 504 of openings 182. In one example, the distance from the secondring 502 of openings 184 to the centerpoint 506 may be about 25% of thedistance from the first ring 504 of openings 182 to the centerpoint 506.In other embodiments, the second ring 502 may be closer or further awayfrom the first ring 504.

It will be appreciated that the number of openings included in thesecond ring 154 of openings 184 may affect processing gas flow. In oneexemplary embodiment, as shown in FIGS. 4 and 5, three openings areincluded in the second ring 402, 502. In another embodiment, more thanthree openings are included. FIG. 6 is an end view of a gas flowdistribution receptacle 600 that may be used in the plasma generatorsystem 100 depicted in FIG. 1, according to another embodiment. In thisembodiment, gas flow distribution receptacle 600 is similar to gas flowdistribution receptacle 114 except that four openings are included in asecond ring 602 of openings 184. In still another exemplary embodimentnot depicted, the second ring 602 may include more than four openings.In any case, the openings of the second ring 402, 502, 602 may bedisposed substantially symmetrically about the longitudinal axis (notdepicted in FIG. 4, 5 or 6) that extends through the centerpoint 406,506, 606. In other embodiments, the openings may be disposedasymmetrically, as long as the flow curtain is formed during the plasmastripping process.

Returning back to FIG. 3, each opening 184 of the second ring 154 ofopenings 184 may extend between the inner surface 165 and the outersurface 169 of the gas flow distribution receptacle 114 at a secondangle (β) relative to the longitudinal axis 171. In one exemplaryembodiment, the second angle (β) is less than the first angle (α) atwhich the openings 182 of the first ring 152 of openings 182 aredisposed, and the second angle is in a range of from about 20° to about30°. For example, the second angle (β) may be about 22.5°. In otherembodiments, the second angle may be less than or greater than theaforementioned range. Each opening 184 of the second ring 154 ofopenings 184 may have a diameter that is substantially identical (e.g.,±0.5 mm) to a diameter of an adjacent opening 184 in the second ring154, but is smaller than the diameter of the openings 182 of the firstring 152 of openings 182. In one exemplary embodiment, the openings 184of the second ring 154 of openings 184 are in a range of from about 50%to about 75% smaller than the openings 182 of the first ring 152 ofopenings 182. For example, the openings 184 of the second ring 154 ofopenings 184 may be about 66% smaller. In another exemplary embodiment,the openings 184 may have diameters that range from about 0.5 mm toabout 2.5 mm in size. The openings 184 of the second ring 154 ofopenings 184 may be substantially uniformly sized (e.g., ±0.5 mm) or,alternatively, may vary within a size range.

Turning to FIG. 7, in an exemplary embodiment, a gas flow distributionreceptacle 700, similar to gas flow distribution receptacle 114,includes a center opening 712 in addition to the first and second rings704, 702. The center opening 712 is located at a centerpoint 706 of arounded section 708 of the receptacle 700. In one exemplary embodiment,the center opening 712 has a diameter that is smaller than the diametersof the openings of the first and the second rings 704, 702. For example,the diameter of the center opening 712 may be in a range of from about0.5 mm to about 1.5 mm. In another embodiment, the diameter of thecenter opening 712 is substantially equal (e.g., ±0.5 mm) to a diameterof an opening of the second ring 702.

As briefly mentioned above, by including the second ring 154 of openings184, 402, 502, 602, 702 and, optionally, the center opening 712, on thegas flow distribution receptacle 100, 400, 500, 600, 700, a flow curtainforms to prevent a majority of ionized gas circulating in the plasmachamber 118, and in particular, reactive radicals in the plasma chamber118, from depositing or contacting the gas flow distribution receptacle100, 400, 500, 600, 700 during a plasma stripping process. FIG. 8 is adiagram depicting flow of a processing gas through a gas flowdistribution receptacle 800 that was constructed similar to the gas flowdistribution receptacle 700 described above. The gas flow distributionreceptacle 800 had a first ring of openings that included twenty-four(24) openings 804. Each opening 804 of the first ring extended throughthe receptacle 800 at an angle of about 45° from the longitudinal axis871 and had a diameter of about 1.5 mm. The center opening 812 had adiameter of about 1 mm. The second ring of openings was disposedsubstantially equidistantly (e.g., ±0.5 mm) from the first ring ofopenings and the center opening 812 and had three (3) openings. Eachopening 802 of the second ring of openings extended through thereceptacle 800 at an angle of about 22.5° from the longitudinal axis andhad a diameter of about 0.8 mm. The processing gas included a mixture ofO₂, N₂, and CF₄, and was flowed into the receptacle 800 at a flow rateof about 100 m/s.

As illustrated in FIG. 8, a first portion of the processing gas flowedthrough the openings 804 of the first ring of openings into the plasmachamber 808 and then recirculated and carried reactive radicals towardthe receptacle 800. A second portion of the processing gas flowedthrough the openings 802 of the second ring of openings and through thecenter opening 812. This second portion of the processing gas thendivided such that some of the gas flowed into the plasma chamber 808 andsome remained close to the surface of the gas flow distributionreceptacle 800 to create a flow curtain (indicated by dotted line 814)thereover. The flow curtain 814 pushed the recirculated gas from theplasma chamber 808 away from the receptacle 800 to swirl in the chamber808, rather than contact the receptacle 800.

As noted above, the plasma generator system 100 may be used for plasmastripping processes. FIG. 9 is a flow diagram of a method 900 ofperforming a plasma stripping process, according to an exemplaryembodiment of the present invention. First, processing gas is flowedthrough openings, such as openings 182 of the first ring 152 of openings182 shown in FIGS. 1-3, formed in a gas flow distribution receptacle,step 902. In an exemplary embodiment, the processing gas comprises oneor more gases that may be ionized to form reactive species that can bedeposited onto the workpiece to remove unwanted organic materialtherefrom. The particular gas selected for the processing gas may dependon the particular organic material to be removed. In an exemplaryembodiment, the processing gas includes a fluorine-comprising gas.Examples of fluorine-comprising gases suitable for use include nitrogentrifluoride (NF₃), sulfur hexafluoride (SF₆), hexafluoroethane (C₂F₆),tetrafluoromethane (CF₄), trifluoromethane (CHF₃), difluoromethane(CH₂F₂), octofluoropropane (C₃F₈), octofluorocyclobutane (C₄F₈),octofluoro[1-]butane (C₄F₈), octofluoro[2-]butane (C₄F₈),octofluoroisobutylene (C₄F₈), fluorine (F₂), and the like. In anotherembodiment, the processing gas may additionally comprise anoxygen-comprising gas. For example, the oxygen-comprising gas mayinclude, but is not limited to, oxygen (O₂) and N₂O. In otherembodiments, the processing gas may additionally comprise an inert gas,such as, for example, nitrogen (N₂), helium, argon, and the like. In oneexemplary embodiment, the processing gas may be a mixture of gases, suchas O₂/N₂/CF₄ at a ratio of 20:8:1 by flow percent. In other embodiments,the mixture may include different ratios of the aforementioned gases. Instill other embodiments, different gases and different ratios may beused.

In an exemplary embodiment, a first portion of the processing gas flowsthrough a first ring of openings of the gas flow distribution receptacleinto a plasma chamber in flow communication therewith, step 904. Eachopening of the first ring of openings extends through the gas flowdistribution receptacle in a manner substantially similar to thedescriptions above with respect to FIGS. 2-7. In particular, eachopening may be formed at a first angle relative to a longitudinal axisthat extends through a centerpoint of a rounded section of thereceptacle. In an exemplary embodiment, the first angle at which eachopening of the first ring of openings is formed is in the range of fromabout 30° to about 60° relative to the longitudinal axis. Each openingmay have a diameter that is substantially identical (e.g., ±0.5 mm) to adiameter of an adjacent opening in the first ring.

An electric field is applied to the processing gas to transform theprocessing gas into an ionized gas including reactive radicals, step906. In an exemplary embodiment, a coil around the plasma chamber isenergized to form an electric field. The electric field extends acrossthe plasma chamber to form a plasma zone. As the processing gas flowsinto the plasma zone, a portion of the gas ionizes to form plasma, andthe plasma dissociates another portion of the gas to form reactiveradicals. For example, in an embodiment in which the processing gasincludes a fluorine-comprising gas, a portion of the fluorine-comprisinggas ionizes to form plasma. The remaining portion of thefluorine-comprising gas may be dissociated by the plasma and transformedinto reactive fluorine radicals. In an exemplary embodiment of thepresent invention, some of the reactive fluorine radicals may flowthrough the plasma chamber, through a showerhead, and may deposit on theworkpiece, while another portion of the reactive fluorine radicals mayrecirculate within the plasma chamber before depositing onto theworkpiece.

To prevent a majority of the ionized gas including the reactive radicalsin the plasma chamber from depositing onto the outer surface of the gasflow distribution receptacle, a flow curtain is formed thereon, step908. In an exemplary embodiment, a second portion of the gas flows intothe plasma chamber through a second ring of openings formed in therounded section between the centerpoint of the rounded section and thefirst ring of openings, step 910. Each opening of the second ring ofopenings is formed substantially identically as described above withrespect to FIGS. 2-7. In particular, each opening of the second ring ofopenings extends through the gas flow distribution receptacle at asecond angle relative to the longitudinal axis that is less than thefirst angle. In an exemplary embodiment, the second angle at which eachopening of the second ring of openings is formed is in a range of fromabout 20° to 30° relative to the longitudinal axis. In anotherembodiment, the second angle at which each opening of the second ring ofopenings is formed is about 22.5° relative to the longitudinal axis.Each opening may have a diameter that is substantially identical (e.g.,±0.5 mm) to a diameter of an adjacent opening in the second ring andthat is less than the diameters of each opening of the first ring ofopenings.

In an optional embodiment, a third portion of the gas flows into theplasma chamber via a center opening formed in the center of the gas flowdistribution receptacle on the longitudinal axis to form another portionof the flow curtain, step 912. The center opening may have a diameterthat is less than that of the openings of the first and second rings ofopenings, in an embodiment. In another embodiment, the center openinghas a diameter that is substantially equal (e.g., ±0.5 mm) to that ofthe openings of the second ring of openings.

As mentioned briefly above, the ionized gas is then deposited onto theworkpiece, step 914. For example, the ionized gas, including reactiveradicals, flows from the plasma chamber, through the showerhead, ontothe workpiece.

Hence, an improved plasma generator system has been provided that may beused in conjunction with fluorine-comprising processing gases withreduced etching of the system components, as compared with conventionalplasma generator systems. Additionally, improved gas flow distributionreceptacles having improved useful lives as compared to components ofconventional plasma generator systems have been provided. The inclusionof these improved gas flow distribution receptacles may decreasemaintenance costs of plasma generator systems.

While at least one exemplary embodiment has been presented in theforegoing detailed description of the invention, it should beappreciated that a vast number of variations exist. It should also beappreciated that the exemplary embodiment or exemplary embodiments areonly examples, and are not intended to limit the scope, applicability,or configuration of the invention in any way. Rather, the foregoingdetailed description will provide those skilled in the art with aconvenient road map for implementing an exemplary embodiment of theinvention. It being understood that various changes may be made in thefunction and arrangement of elements described in an exemplaryembodiment without departing from the scope of the invention as setforth in the appended claims.

1. A gas flow distribution receptacle for providing gas flow to a plasmachamber for forming an ionized gas, the gas flow distribution receptaclehaving a rounded section comprising: an inner surface defining areception cavity; an outer surface forming an enclosed end of therounded section; and a centerpoint on the outer surface, the centerpointhaving a longitudinal axis extending therethrough and through thereception cavity, wherein the rounded section further includes a firstring of openings and a second ring of openings adapted to provide flowcommunication with the plasma chamber, each opening of the first ring ofopenings extending between the inner surface and the outer surface at afirst angle relative to the longitudinal axis mad having a diameter thatis substantially identical to a diameter of an adjacent opening in thefirst ring of openings, the second ring of openings disposed between thefirst ring of openings and the centerpoint and configured to form a flowcurtain over the outer surface of the receptacle to substantiallyprevent contact between the ionized gas and the outer surface of thereceptacle, each opening of the second ring of openings extendingbetween the inner surface and the outer surface at a second anglerelative to the longitudinal axis that is less than the first angle andhaving a diameter that is substantially identical to a diameter of anadjacent opening in the second ring of openings and smaller than thediameters of an opening of the first ring of openings.
 2. The gas flowdistribution receptacle of claim 1, wherein the diameter of each openingof the second ring of openings is about 66% of the diameter of eachopening of the first ring of openings.
 3. The gas flow distributionreceptacle of claim 1, wherein the first ring of openings includestwenty to thirty openings.
 4. The gas flow distribution receptacle ofclaim 1, wherein the first angle is in a range of from about 30° to 60°relative to the longitudinal axis.
 5. The gas flow distributionreceptacle of claim 1, wherein the second angle is in a range of fromabout 20° to 30° relative to the longitudinal axis.
 6. The gas flowdistribution receptacle of claim 1, wherein the second ring of openingscomprises a plurality of openings disposed symmetrically about thelongitudinal axis.
 7. The gas flow distribution receptacle of claim 1,wherein the second ring of openings comprises a plurality of openingsdisposed symmetrically about the longitudinal axis and the second angleof the second ring of openings is about 22.5° relative to thelongitudinal axis.
 8. The gas flow distribution receptacle of claim 1,wherein the second ring of openings is equidistant from the first ringof openings and the centerpoint of the rounded section.
 9. The gas flowdistribution receptacle of claim 1, wherein the second ring of openingsis formed closer to the centerpoint of the rounded section than to thefirst ring of openings.
 10. The gas flow distribution receptacle ofclaim 1, further comprising a center opening formed at the centerpointof the rounded section.
 11. The gas flow distribution receptacle ofclaim 10, wherein the center opening has a diameter that issubstantially equal to the diameter of a first opening of the secondring of openings.
 12. A plasma generator system for forming an ionizedgas, the system comprising: a container defining a plasma chamber, theplasma chamber having an inlet and an outlet; a gas flow distributionreceptacle disposed within the inlet of the plasma chamber, the gas flowdistribution receptacle having a rounded section comprising: an innersurface defining a reception cavity; an outer surface forming anenclosed end of die rounded section; and a centerpoint on the outersurface, the centerpoint having a longitudinal axis extendingtherethrough and through the reception cavity, wherein the roundedsection further includes a first ring of openings and a second ring ofopenings adapted to provide flow communication with the plasma chamber,each opening of the first ring of openings extending between the innersurface and the outer surface at a first angle relative to thelongitudinal axis and having a diameter that is substantially identicalto a diameter of an adjacent opening in the first ring of openings, thesecond ring of openings disposed between the first ring of openings andthe centerpoint and configured to form a flow curtain over the outersurface of the receptacle to substantially prevent contact between theionized gas and the outer surface of the receptacle, each opening of thesecond ring of openings extending between the inner surface and theouter surface at a second angle relative to the longitudinal axis thatis less than the first angle and having a diameter that is substantiallyidentical to a diameter of an adjacent opening in the second ring ofopenings and smaller than the diameters of an opening of the first ringof openings; a coil surrounding the container; and an energy sourceelectrically coupled to the coil.
 13. The system of claim 12, whereinthe first angle is in a range of from about 30° to 60° relative to thelongitudinal axis.
 14. The system of claim 12, wherein the second angleis in a range of from about 20° to 30° relative to the longitudinalaxis.
 15. The system of claim 12, wherein second ring of openingscomprises a plurality of openings disposed symmetrically about thelongitudinal axis and the second angle of the second ring of openings isabout 22.5° relative to the longitudinal axis.
 16. The system of claim12, wherein the container and the gas flow distribution receptacle areintegrally formed.
 17. The system of claim 12, further comprising acenter opening formed at the centerpoint of the rounded section.
 18. Agas flow distribution receptacle for providing gas flow to a plasmachamber for forming an ionized gas, the gas flow distribution receptaclehaving a rounded section comprising: an inner surface defining areception cavity; an outer surface forming an enclosed end of therounded section; a means for providing flow communication between thereception cavity and the plasma chamber; and a means for forming a flowcurtain over the outer surface of the receptacle to substantiallyprevent contact between the ionized gas and the outer surface of thereceptacle.